The proposed study measures auditory, speech, cognitive and academic development and self-esteem in deaf adolescents who received a cochlear implant in preschool. In the past, individuals with prelingual profound deafness have often exhibited substantial educational delays, even in the presence of normal cognitive ability. Such students exhibit 4-6-year average delays in English language and literacy development throughout high school and speech that is minimally understood by inexperienced listeners. These delays have been associated with reduced vocational opportunities and isolation from the majority hearing culture. The advent of cochlear implant technology may constitute a new era in deaf education. The documented auditory, speech and English language skills of young cochlear implant users greatly exceed those of hearing aid users with similar degree of hearing loss. This study will examine performance of adolescents who are long-term cochlear implant users by following a group of 181 children from across North America who were among the first in the world to receive cochlear implants in preschool. These children were first tested when they were in early elementary school (age 8-9). The proposed study will re-evaluate them when they are in late high school (age 16-17). Because the achievement gap between deaf and hearing students tends to increase with age, the early advantages seen in young cochlear implant users may be found to diminish in adolescence. Little is known about the role of auditory speech perception skills in vocabulary and language comprehension during high school, when language is acquired by reading in addition to listening and watching. We will test a structural model of literacy as students approach adulthood and examine the effects of improved speech perception on predicted outcome. Although self-esteem measures conducted at age 8 and 9 year revealed high levels of perceived self-competence, self-image ratings may decrease in high school, particularly for those who identify with neither a Deaf nor a hearing community. The purpose of the proposed study is to identify those factors that contribute to positive outcomes in high school students with cochlear implants and educational programs that promote these outcomes. In addition we will document the incidence and outcomes associated with discontinued use of a cochlear implant.